Add support for poly data box in clip_box filter

[banesullivan]

Resolve #372 - pinging @craigmillernz

This adds support for using a poly data box to clip a mesh. Why? the clip_surface filter isn't very efficient and the box clipping filter is very efficient. Most of the time, users just want a rotated volume/region of interest and this will provide a really good way to extract those!

from pyvista import examples
import pyvista as pv

# The mesh to clip
mesh = examples.load_airplane()

# Use `pv.Box()` or `pv.Cube()` to create a region of interest
roi = pv.Cube(center=(0.9e3, 0.2e3, mesh.center[2]), 
              x_length=500, y_length=500, z_length=500)
roi.rotate_z(33)

# Runt the box lipping algorithm
extracted = mesh.clip_box(box, invert=False)

p = pv.Plotter(shape=(1,2))
p.add_mesh(box, opacity=0.75, color="red")
p.add_mesh(mesh)
p.subplot(0,1)
p.add_mesh(extracted)
p.link_views()
p.view_isometric()
p.show()

[akaszynski]

Considering the speed and how often clipped data is often square, I think this is a great approach to clipping. Especially for geospatial data.